“Welcome to Venice Jerko.” The greeting is painted in three-foot-high letters on a brick wall along Brooklyn’s legendarily polluted Gowanus Canal, right across from the canal’s first luxury high-rise and its new waterfront promenade.

One recent sunny Sunday, a party of German seminary students and a pair of hotel publicists gathered for a canoe tour. The seminarians had read about the canal in a German travel guide that promised “a romantic sunset on the water.” The publicists were scouting to see if the boutique hotel, opening a few blocks away, might want to include guided canoe trips.

“It could make for a great guest experience,” one of the publicists said. The voyagers carried their canoes past the cafe tables on the promenade, put in below the new boat ramp and paddled off.

The future is flowing in fast on the sleepy little canal, where the wilderness of urban decay that sprouted artists and then artisanal ice cream shops is being tidied and tamed. Stroller traffic on the bridge to Whole Foods grows thick, and the sliding crunch of the concrete factory conveyor belt is falling silent.

Last week, a dredging crane began clawing oily-smelling muck off the bottom: an early stage of a $500 million Superfund cleanup. At the same time, New York City is spending about a billion dollars to reduce sewage discharge into the canal and street flooding around it.

Most important, the city is preparing to unleash a force held largely at bay for the first two decades of the Gowanus renaissance: residential development. Next year, officials expect to propose a broad plan that calls for, among other things, rezoning 43 blocks to allow more buildings like the 12-story high-rise complex on Bond Street across from the Venice graffiti (a one-off that required its own special rezoning).

Developers will have to include 25 percent affordable housing — something much needed in Gowanus, where home prices now rival those next door in Park Slope and Carroll Gardens. They will also have to provide access to the waterfront. Knowing this, the canal’s resident environmental group, the Gowanus Canal Conservancy, has put forward its own proposal for a necklace of parks, playgrounds and preserves.

All this along a sickly body of sluggish, often fetid water that despite years of fitful improvements (the herons and striped bass are back again) still seems like the last place a person might want to live.

Stroller traffic on Carroll Street.Credit
Stephen Speranza for The New York Times

Getting everything done will be difficult. Doing it while preserving the neighborhood’s patchwork charms — the artist studios and craft-makers, the surviving heavy industry, the hypnotic, sulfur-scented quiet of the canal on a Sunday morning — might be impossible.

“There’s something compelling happening in this place, the mix is interesting and creative and we want to preserve it,” said Brad Lander, the city councilman for most of the canal zone, who led an earlier two-year public planning effort. “That’s never easy in planning and zoning.”

Whatever happens next on the canal, it is a safe bet that many people will hate it. This tradition goes back, at least, to the 1850s, when Gowanus Creek was walled in to create the canal, said Joseph Alexiou, author of the 2015 history “Gowanus: Brooklyn’s Curious Canal.”

“There’s the sense along the canal that the person who moved here discovered it,” he said, “and that their discovery is the truest one.”

The Gowanus has been here before. In 2009, the city proposed a rezoning of a smaller area that was projected to create 3,200 new apartments, setting off a land rush. But the next year, the canal was named a federal Superfund site. The future was thrown into uncertainty, and the city shelved its plan.

Since then, the Superfund cleanup has been mapped out, real estate prices have climbed higher and Mayor Bill de Blasio, who took office in 2014, chose Gowanus as one of several city neighborhoods where developers could build bigger if they created affordable housing.

Meanwhile, any questions about whether people will pay good money to live beside a national disaster area were answered with the June 2016 opening of the first high-rise, 365 Bond Street, a sleek, stepped box where a light-filled two-bedroom rents for $5,400.

Those opposed to high-end housing along the canal remain unimpressed. Among them is Linda Mariano, a founder of Friends and Residents of Greater Gowanus. She was recently persuaded to take a stroll along the waterfront walkway, which is open to the public though largely hidden from the street.

“This is not Gowanus,” said Ms. Mariano, a retired art teacher who bought a fixer-upper on President Street in 1974. She brushed past a beach rose in a planter. “This is not the beach,” she said. “We should be retreating from the water, not creating an artificial utopia.”

LEFT: Pasquale Bruno has lived near the canal on Bond Street since 1932. RIGHT: The canal has long been a magnet for waste, like these books tossed on a piling near the Carroll Street Bridge.Credit
Stephen Speranza for The New York Times

The neighborhood should refit old industrial buildings for small manufacturers and artists, Ms. Mariano said. “What Gowanus had — and still has to a certain extent — is what America used to be,” she said. “We made things. We had jobs here, and people could live near where they worked.”

But for people in the new building, this is home. The other day, Kate Eurich, 35, sat on a bench by the water with her Jack Russell terrier, Seamus.

“We knew about the reputation of the canal,” she said, “but we did the starter-apartment-in-New-York thing before. We didn’t want to live someplace without A.C. or a dishwasher.”

As for local jobs, Ms. Eurich’s husband works at a marketing company across the canal on Nevins Street, where not long ago the main businesses were drugs and prostitution. She works from home as an analyst for an online rewards company.

“For him it was the convenience,” she said. “For me it was a brand-new building.” The Welcome to Venice graffiti is a nice splash of local color.

“I can see it from my window,” Ms. Eurich said. “ It makes me feel like I’m living in Brooklyn a little bit.”

So far, the two-block-long promenade is little used. This, however, makes it appealing to a crew of high-schoolers from all over the nicer parts of Brooklyn who converge after school to skateboard and chill.

“We have a group chat and people say, ‘Come to Venice,’” said Aidan McCaul, 14.

Last fall, the Department of City Planning began seeking input on the neighborhood’s future. It held 75 hours of public hearings.

Architecture students from Syracuse University took a canoe tour of the canal last month.Credit
Stephen Speranza for The New York Times

Photo

The Superfund cleanup of the canal is getting underway. A dredge hauled up toxic muck and debris last week.Credit
Stephen Speranza for The New York Times Photo

Across from the new high-rises, graffiti carries reminders of the old Gowanus.Credit
Stephen Speranza for The New York Times

Environmentalists and industries, developers and affordable-housing advocates and housing-project residents weighed in. Artists and makers whose long-undesirable studios are suddenly valuable seek protections like subsidized space in the new buildings. And the Gowanus Dredgers canoe club — the folks who took the seminarians out paddling — want more put-in spots.

The zoning piece of this process will probably grind on for another two years. Officials expect the result to be complex even by the byzantine standards of such things: custom zoning, rather than one-size-fits-all.

For example, the city might allow taller residential buildings on corners, while keeping things as they are on midblock sites with low-slung manufacturing buildings. Where there is already housing, the zoning might not change much, to discourage teardowns that would make tenants vulnerable.

“We want to craft a very fine-grained zoning framework that pleases mostly everybody,” said Winston Von Engel, director of the city planning office in Brooklyn.

Those waiting for the go-ahead include Jared Kushner’s company, a partner in a venture to turn a lot across from Whole Foods into a “game-changing mixed-use project that respects the rich cultural and architectural heritage of the Gowanus.”

But the developer most invested in Gowanus may be Property Markets Group, the largest landowner along the canal. The company started snapping up canalside parcels in 2012, when prospects were murky and financing was hard to get.

“I saw this was changing,” said Rich Lam, Property Market Group’s principal for the Gowanus portfolio. “I knew it had legs, and it’s between some great residential neighborhoods.”

The company has amassed nearly half a million square feet of prime acreage, including the building with the Venice graffiti, still used by its former owners as a garage for plumbers’ trucks. Property Market Group also owns, or is buying, the ghostly remains of the Bayside Fuel Oil Co. and a food-truck parking lot between the ancient bridges on Union Street and Carroll Street.

Mr. Lam estimates that his company’s Gowanus projects could be done in five years, by which time the Superfund cleanup should be in full swing. The prospect of asking tenants to live beside the racket and stench of environmental remediation does not trouble him. Nor does the disintegrating state of the canal’s bulkhead, which property owners will have to rebuild.

The subway bridge over the canal at Smith and Ninth Streets.Credit
Stephen Speranza for The New York Times

Mr. Lam, who grew up in Carroll Gardens with a healthy fear of the canal, stood on the rust-scabbed Union Street drawbridge, long overdue for replacement. Could he see any reason, he was asked, that Gowanus’s transformation would not proceed?

“I don’t think so,” he said. A minute later, as if on cue, a three-foot chunk of rotten wooden piling crumpled into the canal with a splash.

The 2010 addition of the Gowanus to the federal Superfund list of the nation’s worst hazardous waste sites followed more than a century of insult and injury at the hands of gas plants, chemical makers and tanneries.

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It took another six years for work to begin. Last fall, in a test area behind Whole Foods known as the Fourth Street Basin, contractors fished out the first debris: the 63-foot hulk of a former ferry where artists held exhibitions and parties in the canal’s wilder days. Now they are dredging the basin to scoop up 10 feet of black sediment heavily laced with coal tar.

The cleanup of all 1.8 miles of the canal, overseen by the government but paid for by polluters and the current owners of their properties, could take about 10 years, officials said. (The cleanup has already weathered one funding scare under President Trump. But his E.P.A. chief, Scott Pruitt, has said that running Superfund cleanups is one of few things the agency should be doing.)

The canal’s health is getting a big boost from the city, too. For example, a pair of huge underground holding tanks are expected to reduce the flow of raw sewage into the canal to a relative trickle of 11 million gallons a year, down from the present 26 million gallons.

One sewage tank is to be built beneath a gravel lot where the city now stores road salt in a giant shed. It is here that the Gowanus Canal Conservancy hopes to build an education center at the hub of what it calls “N.Y.C.’s next great park,” a network of oases strung one after another on both banks of the canal.

The conservancy’s Gowanus Lowlands manifesto conjures a dreamscape of sloping grassy knolls, maritime meadows, performance spaces and picnic spots. The reality will probably be a bit different, but the city has said it will push developers to create varied ways to enjoy the waterfront, beyond the paved walkways and benches behind Whole Foods and the Bond Street high-rises.

A concrete plant near new luxury high-rises.Credit
Stephen Speranza for The New York Times

The conservancy has planted a down payment on its vision: a tiny marsh of native grasses by the salt shed. “Every plug grew,” said the group’s director, Andrea Parker. “Some of them were pulled out by geese, but that was the only mortality.”

“We haven’t been here since 1956!” Patty Condello, a retired garbageman, yelled as he cut the motor.

“We used to make rafts and float them out here,” said his friend George Franqui, 76. “We called ourselves the Gowanus Patrol. We made our own flag. It was a white sheet we took off somebody’s washing line, with the name painted on it.”

Back then, the men said, the canal water was black. “All you could see was a big cesspool,” Mr. Condello said. “And bubbles coming up,” Mr. Franqui added.

The more industrial southern half of the canal zone, where artisans of the new Brooklyn have put down roots among the lumber yards and pickle distributors, is outside the district the city plans to rezone. But many people there are feeling vulnerable anyway.

By the Ninth Street Bridge there is a hive of enterprise that is home to a carpenter’s shop, an amusement-park operator and a two-story foundry called Serett Metalworks.

Cole Keefe, 16, meets his friends at “Venice,” on the promenade behind the new high-rises.Credit
Stephen Speranza for The New York Times

Downstairs, Serett makes things like gates for city parks. Upstairs is a workshop testifying to the interests of Serett’s owner, Josh Young. One recent Friday afternoon, a sculptor was working on a Trump-faced gargoyle. In a corner workstation were two subtenants, glassblowers who specialize in brain-meltingly elaborate bongs. An artist from Queens with a commission for a monumental entranceway to the country’s biggest industrial park, in Nevada, dropped by with blueprints.

Despite all this commerce, it is only a matter of time, Mr. Young said, before he and his neighbors are pushed out.

“There’ll be no industry left here,” Mr. Young said. “This is just counting days, or months, or a year or more. It will all be commercial — Starbucks and JCPenneys.”

City planning officials say that a little more commercial development wouldn’t hurt the industrial zone. “You need a place for people to buy a sandwich and coffee,” Mr. Von Engel, of the city planning office, said.

But Mr. Young’s fears are being realized across Ninth Street from his metal shop, in what was until 2015 a three-building warren of artists, musicians and filmmakers.

The buildings are being turned into an office complex called Roulston House that will feature rooftop lounges and a “fun” ground-floor retail business, maybe a sports bar or bowling alley, the developer says.

In the upper half of the canal zone, an avatar of the new Gowanus economy is flourishing: Genius, a start-up that began as a song-lyric annotation website but aims to be “the ultimate companion to music.” Genius’s 15,000-square-foot headquarters includes video studios and an auditorium where the rapper Pusha-T performed last month. There is a basketball court in the yard where visiting artists shoot hoops with the staff. “We couldn’t have done this in Union Square,” said Ben Gross, Genius’s chief strategy officer.

Someone studying what it takes to survive along the canal might consider the case of the Gowanus Dredgers canoe club.

When the Dredgers were founded in 1999, they were widely regarded as kooks. But they believed the canal was worth saving, and they appealed to anyone they thought could help.

Miguel Pinzon works on a gargoyle at Serett Metalworks, a tenant of an industrial park near the canal.Credit
Stephen Speranza for The New York Times

The Dredgers testified in favor of the Lightstone Group’s high-rise on Bond Street at land-use hearings. This earned them scorn in the neighborhood. But the site was largely abandoned, and that wasn’t helping the canal, said Owen Foote, treasurer and co-founder of the Dredgers.

“We felt that having people living in close proximity to the waterway was better than having a truck parking lot,” he said.

Lightstone was impressed by the Dredgers. “We felt they were playing a vital role in terms of revitalizing the canal,” said Mitchell Hochberg, Lightstone’s president.

This is how the photos in the window of the leasing gallery at 365 Bond Street came to include, along with the usual shots of the roof deck and the stainless-steel kitchen appliances, one of a young couple canoeing on the canal.

And it is how the Dredgers came to inhabit a window-lined boathouse in the ground floor of the complex, practically rent-free. They offer free canoe rides to the public every Saturday, through the end of October.

Mr. Foote’s next plan is to see if the other high-rise next door will let him offer children’s kayak lessons in the rooftop pool.

Late one Friday afternoon in September, there were 400 people jammed into the yard of an outdoor barbecue joint on the bank of the canal called Pig Beach, where a rack of baby back ribs is $34.

It was not a special event, just a nice day. The line for ribs snaked almost back to the “No Fishing” sign on the fence. Where did all these people come from? “Queens, Williamsburg, a lot of Manhattanites, the Bronx,” said the bouncer, Cam King.

“I was wondering that myself,” said a man who grew up in the neighborhood when it was all Italian. “There’s no one from Brooklyn in the place.” The woman in line in front of him turned and said she had grown up a few blocks away. She was Samantha MacIvor, 40, a stuntwoman. He was John Musumeci, 60, a union carpenter. They got talking and figured out they’d been neighbors for decades without meeting.

“Out the back of my building we could see each other!” Mr. Musumeci said. “Do you know Jerry Ears?” Ms. MacIvor asked.